Conventionally, a wire harness that is laid at a position exposed to the outside of a vehicle, e.g. an automobile, such as a lower surface of the bottom plate (underflooring) of the vehicle, sometimes includes an electric-wire protection pipe that is made from metal and surrounds the electric wires. The electric-wire protection pipe protects the electric wires from foreign substances such as gravel flying up from the road, and functions as an electromagnetic shielding pipe for shielding from noisy electromagnetic waves. Therefore, the electric wires inserted into the hollow part of the electric-wire protection pipe are usually unshielded electric wires. “Unshielded electric wire” refers to an insulated electric wire that is not covered with a shielding member, such as a braided wire.
Furthermore, the electric-wire protection pipe that is laid out at the bottom plate of the vehicle has to meet the following requirements. First, the electric-wire protection pipe is required to have a hollow part whose internal cross-sectional area is sufficiently large for the plurality of electric wires to be inserted into the hollow part. Furthermore, the electric-wire protection pipe is required to have an outer shape with a projection height from the lower surface of the bottom plate that is as low as possible.
In order to meet the above-described requirements, it is conceivable to use, as an electric-wire protection pipe, a metal pipe having a flat outer shape. For example, the electric-wire protection pipe disclosed in Patent Document 1 is a metal pipe having a flat outer shape that is obtained by performing press working on a round pipe having a circular cross-sectional shape.